Hall Effect and Magnetism Glossary

The Hall Effect and magnetism subject can be a tricky one to understand, with a large number of complicated phrases. Let’s simplify them one by one, A to Z.

A

Active Area – This is the description and measurement of a transducer which is used to measure a field of magnetism. The most common measurement is around 0.5mm.

Air Gap – The measurement between the magnet and the outer of a sensor.

Alnico – There are many Alnico-type magnets around becuase they are considered to be duarable and energy conserving. This is a material of which a magnet is made, often comprising of three metals – nickel, cobalt, and aluminium.

Ampere – A measurement of a current, per second.

Ampere-tum – An ampere (see above) which travels through one revolution of a wire.

Amperes/meter (A/m) – This is another measurement but this measures the strength and overall intensity of the magnetic field, rather than it’s size.

Anisotropic (Oriented) – This is a type of magnet which is able to carry a higher amount of magnetisation.

Auto-Nulling/Auto-Zeroing – A way to alter the makeup of a system, which allows the user to measure any offset errors which may occur, and then prevent them from occuring.

B

Bandwidth – We hear about bandwiths a lot with radio signals, and basicaly this is a range of a frequency. This range allows signals to travel along them, for communication purposes usually. A faster performance requires a high bandwith.

B-H curve – This is an arc, or curve, of magnetic flux density.

Bipolar – When a material posses two separate polarities, e.g. positive or negative.

Bipolar Switch – A sensor which has magnetic switches which are different, e.g. positive or negative.

Bipolar IVansistor – This is a transister which has three different layers of conductor, e.g. the emitter terminal, the base, and the collector terminal.

C

Capacitor – This is a circuit which has two different plates of conductivity, with an insulator sandwiched between them. The insulator is used to store energy.

Hysteresis – The range between signal on input when it is turn on and off.

Hysteresis Loop – A B-H curve shape which doesn’t overlap. The larger the loops, the more coercivity.

Hysteresis, Magnetic (Bh) – Used in Hall Effect sensors of the digital variety, this is the flux density and turn on point difference.

I

Impedance – Resistance against electricity measurement.

Inductor – A part of a circuit which has loops of wire, one or sometimes more, which hold energy and magnetic fields.

Instrumentation Amplifier (lA, InAmp) – This is a device, an amplifier, which has a high amount of gain and has different input types. Transducer signals are amplified using this device.

Intrinsic Coercive Force (H^i) – The part of a material which is resistant to becoming demagnetised, and its accompanying measurement.

Intrinsic Induction (Bi) – This is the measurement of difference between the induction of magnetisation and the force of magnetisation.

Irreversible Losses – This is when a material loses much of its magnetic properties (a permanent magnet), but can be often regained when it is remagnetised.

Isotropic (Unoriented) – This is a magnet which can be magnetised to any amount, in any particular direction.

K

Keeper – This is a type of steel which protects the magnetic area around a type of magnet, and is often used whilst a magnet is being transported, or stored. This is for protection and needs to be made of a strong material, which will not be demagnetised whilst in storage or en route to a destination.

L

Latch – A type of Hall Effect sensor that has opposite polarity points. These can be switched to on or off.

Leakage Flux – When a magnetised circuit loses magnetic flux, this is referred to as leakage flux and can be measured in a large or small amount.

Linear Hall-Effect Sensor – This is a type of Hall Effect sensor which gives an output which is direct to the magnetic field it is measuring.

M

Magnet Conditioner – A piece of equipment which demagnetises magnets in a slow and controlled manner.

Magnetic Field Intensity (H) – The measurement of a magnet’s ability to create a magnetic field, and how strong it is as a result.

Magnetic Flux – The total over an area of flux density.

Magnetic Flux Density (B) – This is often referred to as the magnetic field, and it is measured using a separate device, i.e. a gaussmeter.

Magnetizer – A piece of equipment that creates magnetic fields, which are often quite strong and long-lasting.

Maximum Energy Product – When a material is demagnetised, this is the particular point where B and H reach their peak point, i.e. the maximum energy.

Maximum Service Temperature – A magnet’s maximum temperature at which it can operate without becoming damaged or broken beyond all repair.

Maxwell – A measurement of magnetic flux.

MOS IVansistor – MOS stands for metal-oxide semiconductor transistor. This is a piece of equipment which is used to create digital logic.

Mu-Metal – A magnet which is made of nickel and iron primarily.

Multipole – This is a magnetic which has in excess of two poles, i.e. more than the standard type of magnet.

N

Neodymium-Iron-Boron (NdFeB) – A type of material which is often used to create strong and durable magnets.

Noise – This is often referred to as interference, and is a sound or signal that doesn’t pay any positive point to your measurements. Noise is not useful in this regard.

O

Oersted (Oe) – A mesurement which is used to measure the strength of a magnetic field.

Offset Error – This is an error measurement and is created by subtracting away the actual signal measurement from the error signal measurement, to give you the offset error amount.

Ohm’s Law – A scientific theory which states that voltage = resistance, multiplied by current.

Operational Amplifier – A type of amplifier which creates a large amount of gain.

Open-Loop – A system when the result is not measured, but is instead there to create and offset, in order to create the a desirable output amount.

Operating Point – This is the point on a circuit which gives information on the B and H of the magnet.

P

Permalloy – A magnet which is made of nickel and iron.

Permeability – Magnetic flux desnity and magnetic field intensity, and how well or otherwise they work together.

Power-On Recognition – Usually in a geartooth type of sensor, this is a function which means turning on a sensor is recognised.

Proximity Sensor – A piece of equipment which informs you of a target being nearby, or far away.

Q

Quadrature – The point at which two separate signals are not within sync. This is often due to rotation.

Quiescent Output Voltage – This is measured by a sensor and is the output of the voltage, when there is no other magnetic field detected.

R

Rare-Earth Magnet – This is a type of magnet which is made with a different type of material, e.g. samarium, which is considered to be a little more difficult to melt into a suitable form of material for a magnet. These types of magnet are however considered to be high quality.

Reference Magnet – This is a type of magnet which has been changed, in order for it to detect and create a particular type of magnetic field. This type of magnet is much more flexible, because it can be ‘programmed’, i.e. to measure magnetisation when calbirating equipment, for instance.

Release Point – The magnetic flux desnity measurement when a Hall Effect sensor, usually digital, turns itself off. This measurement is the release point.

Remanent Induction – The measurement obtained after a material (one which possesses magnetic value) has undergone saturation. The remaining number is the remanent induction.

Resistor – This is a piece of equipment which has two separate electrodes and creates a block to the current flow. This means that a particular voltage measurement can be achieved.

Ring Magnet – This is a type of magnet which is, as the name would suggest, designed in a ring shape. This type of magnet has several poles, rather than the standard two.

S

Samarium-Cobalt – A rare and difficult to use material, which when successfully created, helps to make extremely strong and durable types of magnets.

Saturation – A circuit has a saturation point, and this is when the signal fails to result in a rise in the output signal.

Search Coil – A search coil is a wire coil which makes up part of a fluxmeter, acting as a transducer. When flux ebbs and flows as it goes through the search coil, this gives out a voltage.

Self-Demagnetization – This happens when a magnet has an breakage or disruption in the fluxpath. This means that flux desnity is reduced, and the magnet becomes less effective.

Semiconductor – This is a material which successfully conducts power, or electricity, but one which isn’t as effective as the regular type of material, e.g. metal. A semiconductor type of material is often a silicone, but are often used to create Hall Effect sensors or transducers.

Sensitivity – This is a measurement of the effect when an output is put against an input. Again this, is used in Hall Effect sensors, and can be loosely compared to gain.

Sensor – This is a piece of equipment which produces a measurement, e.g. the measurement of a magnetic field.

SI – SI is a term which groups together different measuremen4t units, e.g. kilograms (kg), seconds (s), meters (m), etc. This is the international grouping term.

Slide-By – A function which senses the closeness, or distance, from a pole of a magnet, as it moves past the sensor. This movement is parallel to the facing side of the sensor.

Speed Sensor – This sensor, as the name would also suggest, measures and detects movement, or specifically, speed.

Surface-Mount Device (SMD) – This is a device which is electronic and is fixed to the circuit board of another device.

Switch – This is a type of Hall Effect sensor that is turned off when there is no magnetic field to be detected. It also turns itself back on only when the flux density minimum amount is above and beyond.

T

Temperature Coefficient – This is the amount at which a magnet changes in behaviour according to a change in temperature.

Tesia – This is a measurement unit of magnetic flux density.

Thermal Demagnetization – When a magnet is exposed to too much heat, it becomes demagnetised and therefore damaged. Thermal demagnetisation is the term of this occurence.

Toroid – This is a round shaped device, a concentrator of flux, which is more often than not used to create a sensor, e.g. a Hall Effect sensor.

Total Effective Air Gap (TEAG) – This is the measurement of space on a magnet (the surface area) to the transducer itself.

Transducer – This is a piece of equipment which converts effort into power. For instance, a Hall Effect transducer detects a magnetic field and then turns it into a voltage output. The main piece of equipment this can be compared to is a motor, when voltage is used to create rotation, e.g. turning the motor.

TTL – Transistor-Transistor Logic – This type of circuit is now very rarely used, but is a logic type of circuit.

Two-Wire Interface – An electrical board which uses two wires only, hence the name. Instead of using voltage to give information, this type of equipment uses current changes intead.

U

Unipolar – A piece of equipment which has one polarity only, as opposed to bipolar, which has two.

Unipolar Switch – This is a type of Hall Effect sensor which ensures that the BQP and BRP both use the same form of polarity, e.g. bipolar or unipolar.

V

Vane – This is a piece of equipment which works as a target. This causes a blockage beween the magnetic field between the sensor and the actual magnet itself.Z

Zero-Flux Output Voltage – This term relates to the voltage which is measured by a sensor when there is no magnetic field detected. This term is also sometimes known quiescent output voltage too, but refers to the same thing.